Somatic cell nuclear transfer in its first and second decades: successes, setbacks, paradoxes and perspectives

Abstract

The present review gives a subjective outline of the past and future of somatic cell nuclear transfer (SCNT). The first decade was full of contradictions: amazing successes were followed by frustrating fiascos. Although the possibility of reversing somatic cell differentiation completely is a more or less acknowledged fact, the underlying mechanisms are obscure. Consequently, the advancement has been mostly empirical and rather slow. Efficiency is slowly increasing in some species while stagnating in others, and the technology is too expensive for most practical purposes. The number of cloning laboratories is rather small, and those with reasonable productivity are extremely rare. SCNT research is underfinanced because of the atmosphere of suspicion surrounding cloning and the controversial reputation of cloners. However, certain signs may indicate a more successful next decade. In some species, technical refinements have resulted in a considerable decrease in developmental anomalies. Even the actual efficiency seems to be suitable for special purposes with high scientific and commercial impact including transgenic domestic animal production for human disease models, xenotransplantation and biopharming. Human therapeutic cloning is now a realistic perspective, and certain responsible scientists have started to question the reasonableness of an eternal ban for human reproductive cloning. Just one fulfilled goal out of the many promises of SCNT would justify the invested efforts.

Embryonic Development and Implantation Related Gene Expression of Oocyte Reconstructed with Bovine Trophoblast Cells

“…Many cloned offspring have been produced using several types of donor cells including fibroblasts to date [1,3,29]. Most embryonic or somatic cells are reprogrammed in enucleated oocytes and develop into preimplantation embryos with different efficiencies.…”

“…Dev. 58: [425][426][427][428][429][430][431] 2012) S ince the first cloned lamb was born, nuclear transfer (NT) has been challenging in several species and has produced many cloned offspring [1][2][3]. To produce cloned offspring, fetal fibroblasts have been chosen as a preferential donor cell line for NT so far because they have high proliferative potentials [4][5][6][7].…”

Ethical Aspects of Tissue Engineering: A Review

“…And although there are strong indications that it is in principle possible to acquire human blastocysts through somatic cell nuclear transfer, 138 it is as yet far from evident that it will be possible to obtain in a safe and efficient way differentiated cells, let alone tissues or organs, derived from hESCs acquired via therapeutic cloning. 20,139,140 In other words, the strong focus of the debate on the issues of hESCs and therapeutic cloning is not warranted.…”

S-adenosylhomocysteine treatment of adult female fibroblasts alters X-chromosome inactivation and improves in vitro embryo development after somatic cell nuclear transfer

“…While this technique has been successfully applied to a number of species (Vajta 2007), the success rate in terms of the number of live clones per manipulation remains low (1-5%) along with a high incidence of perinatal mortality and unexplained congenital malformations (reviewed by Han et al 2003).…”